Paraffin cleaner for well tubing



23, 1966 D. s. BOD; 3,268,007

PARAFFIN CLEANER FOR WELL TUBING Filed Aug. 16, 1963 INVENTOR.

S. B l E ATTORNEY United States Patent 3,268,007 PARAFFIN CLEANER FOR WELL TUBING Davis S. Bodie, Norman, 0kla., assignor to Cities Service Oil Company, Bartlesville, Okla., a corporation of Delaware Filed Aug. 16, 1963, Ser. No. 302,543 2 Claims. (Cl. 166-170) The present invention relates to a device for preventing paraifin accumulations in the production tubing of producing oil wells. More particularly, it relates to a free falling device which, when used periodically, prevents paraffin deposits from building-up or accumulating.

One of the more important problems encountered in the production of certain types of crude oil is the deposition of paraflin on the inner surfaces of the production tubing used to transport the crude oil to the surface. Such parafiin deposition results primarily from a decrease in oil temperature. At the temperature prevalent at the depth at which the oil is produced, the paraffin contained in crude oil is in the liquid state. As the crude oil flows through the production tubing toward the surface, its temperature decreases until a-point is reached at which the paraffin crystallizes out and accumulates on the walls of the production tubing. If the paraffin deposition is permitted to build up unchecked, the parafiin eventually chokes the tubing and seriouly restricts, or even stops, the flow of crude oil to the surface. When this occurs, a costly and time-consuming paraffin removal operation must be performed.

Several methods have been proposed for combating paraffin deposition. In one common method, cutting tools lowered into the production tubing by means of a wire line cut or scrape parafiin accumulations from the Wall of the tubing. This method is expensive and causes a considerable loss of production during the paraflin removal operation. In another method, called hot oiling, heated oil is circulated in the production tubing. This method is also expensive and causes considerable downtime and loss of production. In still another method, various kinds of paraffin solvents are added to soften the paraffin and to some extent place it back in solution with the crude oil. This method, likewise, is expensive and introduces the possibility of contaminants objectionable to refiners of the crude oil. In addition, some commercial paraflin solvents contain carbon disulfide, a toxic agent hazardous to operating personnel.

In a further method of combating paraflin deposition, free-falling devices, having attached fiber or rubber cups or circular rings which fit tightly against the tubing wall during upward movement of the scrapers periodically pass up and down the production tubing. These devices, called scrapers, require a check valve which permits them to fall freely to the bottom of the well and a flow intermitter at the wellhead to alternately flow and shut-in the flowing well in which the scraper is used.

The object of the present'inven-tion is to provide a device which will prevent any appreciable paraffin accumulation in production tubing.

Another object of the present invention is to provide a free-falling device which may be placed in a production tubing and which by traveling periodically in the production tubing will prevent paraifin from accumulating therein.

Another object of the present invention is to provide a free-falling device for preventing paraffin accumulation in a production tubing in which downtime and loss of production are minimized.

A further object of the present invention is to provide a free-falling device for maintaining a production tubing essentially free of parafiin deposition in which the travel speed of the device in the production tubing can "ice be regulated-in accordance with the parafiin characteristics of the particular crude oil.

Further objects and advantages of the present invention will appear from the detailed description contained herein of the invention and an illustrative embodiment thereof, the novel features of which will be particularly pointed out in the appended claims.

The objects of this invention are accomplished by a free-falling device employing helical springs that vibrate during the periodic travel of the device down and up the tubing, due to the turbulence of the fluid and gas movement through the springs. The vibrating springs contact the inner walls of the production tubing and remove parafiin deposition before any appreciable accumulation occurs.

An embodiment of the present invention is described herein with reference to the accompanying drawings in which:

FIG. 1 is a view partly in elevation and partly in section of the complete device and a catcher adapted to hold the device at the top of the production tubing;

FIG. 2 is a side view of the body portion of the device with the helical springs removed;

FIG. 3 is a bottom view of the body portion of the device taken from along the line 3-3 on FIGURE 2;

FIG. 4 is a side view, partly in section, of a removable plug containing an orifice adapted to be secured in the bore running through the body of the device.

In the illustrative embodiment, and more particularly in FIGURE 1, the numeral 1 represents an elongated body having a main body portion 2, preferably having a circular cross-sectional configuration to conform to that of the production tubing. At each end of main body portion 2 are extended portions 3 having a somewhat smaller cross-sectional diameter than main body portion 2. Mounted on extended portions 3 are helical springs 4 which are of suflicient width so as to contact the sides of the production tubing as they vibrate during the travel of the device up and down the production tubing. The lower spring 4 is preferably bevelled to facilitate its passage down the tubing.

At each end of elongated body 1, holes 5 are provided into which the end of the helical spring legs adjacent main body portion 2 are inserted and secured by Allen head set screws 6, countersunk so the heads of which will be fiush with main body portion 2. After Allen head set screws 6 are made up as tight against the helical spring legs in holes 5 as possible, the recess around the screws may be filled in with low melting point tin solder to lock the screws in place. 4

As shown in FIGS. 2 and 3, elongated body 1 contains a bore 7, one end of which is provided with a threaded portion 8 into which thread plug 9, shown in FIGURE 4, may be secured. Plug 9 is provided with an orifice 10 which permits the passage of well fluid and gas through elongated body 1. By employing various plugs having different orifice sizes, the rate of travel of the device in the well can be regulated.

In order for the present invention to work properly, it is necessary that the production tubing be clean and essentially free of paraffin when the device is installed. If the tubing is dirty, it should be initially cleaned by hot oiling or scraping prior to the installation of the present invention.

After the present invention has been installed, it will travel down the production tubing by its own weight each time the well is intermitted. On wells that are not normally intermitted, it is desirable that an intermitter be installed so that the well may be shut-in periodically to enable the device to fall to the tubing stop set below the par-afiin line in the production tubing. It has been found that generally shutting-in the well four times each day will be sufficient to keep the tubing free from paraflin accumulation. It may be necessary, however, to let the device tr-avel more than four times each day in wells With extreme parafiin problems. The How of the well need only be stopped each time for a sufficient period to enable the device to drop to the tubing stop. This normally takes approximately three minutes. When flow is resumed the device will be carried to the top of the production tubing by the upward flow in the production tubing. Since the paraflin is not permitted to accumulate on the tubing walls to the extent that it causes plugging, the parafiin knocked loose from the walls of the tubing by the vibrating springs does not tend to plug orifice or bore 7.

It is desirable to provide a means for accommodating the device at the surface during those periods in which the device is not traveling down and up the production tubing. A container long enough to accommodate the device can be provided at the top of the flow T on the wells Christmas tree. The flow of oil and gas up the production tubing will tend to maintain the device in such a container until such time as the well is shut-in when the device will fall to the tubing stop by its own weight.

When it is desired to inspect the production tubing or to change the orifice in the body portion of the device, some means for catching the device is needed. A catcher for holding the device at the surface is shown in FIG- URE l in which the container for holding the device is represented by numeral 11. Threaded portions 12 are provided at each end of the container 11, the lower portion being threaded into the top of the flow T on the wells Christmas tree. The upper portion is closed off by means of plug 13. Welded to the side of container 11 is an outside case 14 having a threaded portion 15 on its inner bore. Inside trigger ase 16 is adapted to fit into outside case 14 and is provided with threads 17 which serve to secure inside trigger case 16 to outside case 14 through its threaded portion 15. The end of inside trigger case 16 which is not inserted in outside case 14 is provided with a hexagon end 18 which may be turned by means of handle 26 so as to screw inside trigger case 16 into outside case 14 or to remove said inside trigger case 16 from outside case 14. Inside trigger case 16 has a groove 20 containing 0 ring 21 on its outer surface to provide a seal between outside case 14 and inside trigger case 16.

The end of inside trigger case 16 which is inserted into outside case 14 contains a bore which does not run entirely through the case but which is long enough to con tain the trigger and spring hereinafter described. A threaded plug 22 having an orifice 23 is inserted into the end of the bore in inside trigger case 16. Trigger 24, which serves as a latch to hold the parafiin cleaning device in container 11, is an elongated body one end of which passes through orifice 23 and a hole in container 11 to catch and hold the paraffin leaning device therein. Spring 25 is also provided in the bore in inside trigger case 16 to urge trigger 24- toward container 11. Trigger 24- has a collar which contacts plug 22 to prevent excessive movement of trigger 24 into container 11.

By turning handle 26, inside trigger case 16 may be moved toward container 11, until hexagon end 18 shoulders against outside case 14. This causes plug 22 to move toward container 11, which also perimts trigger 24 to move in the same direction due to the action of spring 25. When handle 26 has been turned to its inmost position, a portion of trigger 24 protrudes into container 11 thereby serving as a latch to hold the paraflin cleaning device in container 11 although the well is shut-in. When it is desired to release the parafiin cleaning device, handle 26 may be turned so as to move inside case 16 away from container 11 thereby forcing trigger 24- to move completely into inside trigger case 16 permitting the paraflin cleaning device to fall freely down the production tubing. Handle 26 may be turned by hand or by suitable auto matic means.

The size of the elongated body and of the helical springs depends upon the size of the production tubing in which the device is to be used. It is generally desirable that the helical springs be at least approximately twice the length of the extended portions of the elonagted body in order that the springs may vibrate sufii'cently when well fluid and gas passes through them to contact the wall of the tubing. A preferable spring length hasbeen found to be between 3 and 4 times the length of the extended portions of the elongated body. Satisfactory results have been obtained when the spring width is approximately the same as the diameter of the main body portion of the device.

The present invention will keep production tubing essentially free from paraifin deposition indefinitely without the use of any other device. As indicated above, the vibrating springs kno k the paraffin from the Walls of the tubing before the parafiin can build up and become solid enough that scraping becomes necessary to remove it. This represents an important advantage of the present invention over those types of free-falling devices that scrape the paraffin from the walls of the tubing. Paraii'in scrapers are sometimes impeded in their travel down a production tubing by the presence of paraifin accumulations on the walls of the tubing, and will occasionally become hung on such paraifin deposits. The present device can, in addition, be made to fit the tubing more loosely than the scraper-type devices, thereby further facilitating its travel down the well tubing.

An additional feature of the present invention is that, by changing the orifice size in the body portion of the device, the travel speed of the device may be regulated. Thus, the device can be made to travel more slowly in wells in which parafrin problems are grave and may be made to travel more quickly in wells in which parafiin deposition is not such a problem. By using a plug having a large orifice, the travel speed of the device may be lessened, and by using a plug having a relatively small orifice, the travel speed of the device may be increased.

It will be understood that various changes in the details and arrangements of parts, which have been herein described and illustrated in order to explain the nature of the invention, may be made by those skilled in the art within the principle and scope of the invention as expressed in the appended claims.

I claim:

1. A device for maintaining an oil well production tubing essentially free from parafiin accumulation comprising:

an elongated body adapted to move freely within the production tubing, said body including a main body portion with extended portions at each end, said main body portion having a cross-sectional size slightly less than that of the production tubing so that the device may freely travel up and down said production tubing, said extended portions having a smaller crossscctional size than the main portion of said elongated body;

helical springs mounted on said extended portions of the elongated body, said helical springs having a width slightly less than that of the production tubing, said width being sufficient so that the springs contact the sides of said production tubing as the springs vibrate during the travel of the device up and down said productioin tubing, the length of said helical springs being at least approximately twice the length of the extended portions of the elongated body;

whereby the device falls freely in a tubing stop due to its own Weight when the well is shut-in and is lifted to the surface by the well fluids and gas when'fiow is resumed, the turbulence caused by fluid and gas movement through the springs ausing said springs to vibrate and contact the inner walls of the production tubing thereby removing parafiin from the walls before any appreicable accumulation occurs.

2. The device of claim 1 in which the elongated body has a bore through which Well fluid and gas may pass thereby contributing to the turbulence that causes vibration of the helical springs during movement of the device up and down the production tubing and including a plug adapted to be fitted into one end of said bore, said plug containing an orifice to permit the flow of Well fluid and gas through the device.

References Cited by the Examiner UNITED STATES PATENTS 613,459 11/1898 Minnemeyer 306-20 X Blum 166170 Silverman 15-104.3

Besse 166176 C'urnutt et al 166170 Reynolds 166-170 X Copas 166-170 X CHARLES E. OCONNELL, Primary Examiner. 10 A. I. CALVERT, J. A. LEPPINK, Assistant Examiners. 

1. A DEVICE FOR MAINTAINING AN OIL WELL PRODUCTION TUBING ESSENTIALLY FREE FROM PARAFFIN ACCUMULATION COMPRISING: AN ELONGATED BODY ADAPTED TO MOVE FREELY WITHIN THE PRODUCTION TUBING, SAID BODY INCLUDING A MAIN BODY PORTION WITH EXTENDED PORTIONS AT EACH END, SAID MAIN BODY PORTION HAVING A CROSS-SECTIONAL SIZE SLIGHTLY LESS THAN THAT OF THE PRODUCTION TUBING SO THAT THE DEVICE MAY FREELY TRAVEL UP AND DOWN SAID PRODUCTION TUBING, SAID EXTENDED PORTIONS HAVING A SMALLER CROSSSECTIONAL SIZE THAN THE MAIN PORTION OF SAID ELONGATED BODY; HELICAL SPRINGS MOUNTED ON SAID EXTENDED PORTIONS OF THE ELONGATED BODY, SAID HELICAL SPRINGS HAVING A WIDTH SLIGHTLY LESS THAN THAT OF THE PRODUCTION TUBING, SAID WIDTH BEING SUFFICIENT SO THAT THE SPRINGS CONTACT THE SIDES OF SAID PRODUCTION TUBING AS THE SPRINGS VIBRATE DURING THE TRAVEL OF THE DEVICE UP AND DOWN SAID PRODUCTION TUBING, THE LENGTH OF SAID HELICAL SPRINGS BEING AT LEAST APPROXIMATELY TWICE THE LENGTH OF THE EXTENDED PORTIONS OF THE ELONGATED BODY; WHEREBY THE DEVICE FALLS FREELY IN A TUBING STOP DUE TO ITS OWN WEIGHT WHEN THE WELL IS SHUT-IN AND IS LIFTED TO THE SURFACE BY THE WELL FLUIDS AND GAS WHEN FLOW IS RESUMED, THE TURBULENCE CAUSED BY FLUID AND GAS MOVEMENT THROUGH THE SPRINGS CAUSING SAID SPRINGS TO VIBRATE AND CONTACT THE INNER WALLS OF THE PRODUCTION TUBING THEREBY REMOVING PARAFFING FROM THE WALLS BEFORE ANY APPREICABLE ACCUMULATION OCCURS. 